1. Field of the Invention
The present invention relates to subsurface well equipment and, more particularly, to devices and related methods for determining the position of subsurface well equipment within a well.
2. Description of the Related Art
Wells having one or more lateral branches extending therefrom are now commonplace in the petroleum-exploration industry. It is customary that it is desirable to enter one or more of the lateral branches with a some type of work or tool string. It is known that a deflecting device have an inclined surface (often called a "whipstock") is used divert the string into the desired lateral, and that the whipstock must be remotely oriented and set in the well bore adjacent the lateral branch into which tool entry is desired. This is often accomplished by use of one or more locating and orienting keys on the whipstock that cooperate with an orienting profile and alignment slot in the well near the desired lateral branch. A problem that exists in this scenario is that current technology does not give a sufficiently reliable indication to an operator at the earth's surface that the whipstock has been properly landed in the alignment slot. In this regard, the current approach to determining whether the whipstock is properly landed is to compare the tension or compression on the string to the length of the string. This is not considered reliable for either coiled tubing or jointed pipes. The accuracy of this approach for coiled tubing is approximately .+-.50 feet and for jointed pipe approximately .+-.10 feet. With these margins of error, the whipstock could be stuck in the wrong place within the well several feet above or below the mating profile, but the surface indication would be that it was properly landed in the correct location.